You enabled the 'bindist' use flag which disables the Firefox branding. firefox-17.0.7 is the most recent stable version for amd64 and x86. If you want a more resent version you need to use the testing version._________________First things first, but not necessarily in that order.

Furthermore why is version of Aurora is 17.x.x when FF is around 22 / 23

17 - is the current ESR relase http://www.mozilla.org/en-US/firefox/organizations/faq/
Basically it means that you've got all the security patches from the latest Firefox, but no new security holes from the features introduced in post esr releases.
For example Tor Browser Bundle is based on Firefox 17 esr.